Formulation and method for brightening aluminum

ABSTRACT

The present invention is directed to an aluminum brightener formulation which includes water, phosphoric acid, a transition metal compound and a wetting agent. Aluminum may be brightened by a method which includes the step of spraying or brushing an aluminum surface with the present formulation at a moderate temperature.

United States Patent 51 May 16, 1971 Ritzi [54] FORMULATION AND METHOD FOR BRIGHTENING ALUMINUM [72] Inventor: Jack Henry Ritzi, Cincinnati, Ohio [73] Assignee: Chemed Corporation, Cincinnati, Ohio [22] Filed: Aug. 13, 1969 211 Appl. No.: 849,906

[52] US. Cl ..156/21,156/22, 252/792, 134/3, 134/41 [51] Int. Cl. ..C23f 3/02 [58] Field of Search ..156/21, 22; 252/792;

[56] References Cited UNITED STATES PATENTS 2,760,891 8/1956 NICIIOIS ..156/21 3,004,056 10/1961 Nunn et a1. ..252/89 3,194,704 7/1965 Hubert 252/792 3,240,633 3/1966 Gowman et al. 148/615 Z 3,301,787 1/1967 Cohn ..156/21 3,448,055 6/1969 Mickelson et a1 156/22 FOREIGN PATENTS OR APPLICATIONS 403,373 12/1933 Great Britain 625,834 7/1949 Great Britain ..156/21 967,207 3/1950 France 1,088,287 10/ 1 967 Great Britain OTHER PUBLICATIONS Metals Handbook 8th Ed. (1961) Vol. 2. pp. 615 and 617 cited.

Primary Examiner-Robert F. Burnett Assistant ExaminerR. J. Roche Attorney-Eugene M. Bond and Kenneth E. Prince [57] ABSTRACT The present invention is directed to an aluminum brightener formulation which includes water, phosphoric acid, a transition metal compound and a wetting agent. Aluminum may be brightened by a method which includes the step of spraying or brushing an aluminum surface with the present formulation at a moderate temperature.

1 Claim, No Drawings This invention relates to a formulation which includes a transition metal compound, phosphoric acid and a wetting agent; and to a method for brightening aluminum therewith.

Cleaning and brightening of metals such as aluminum or its alloys have been effected heretofore using formulations containing high concentrations of offensive and hazardous acids such as nitric, sulfuric, hydrochloric, and particularly hydrofluoric acid. Such formulations present a safety hazard in their preparation and use.

One known method for brightening aluminum involves the use of a dip tank necessarily operated at an elevated temperature to effect the desired brightening in a reasonable amount of time. A dip tank has the limitation that the size of aluminum articles to be cleaned therein is restricted by the dimensions of the tank. Known aluminum brightening formulations and methods frequently cause undesirable streaking of aluminum metals while formulations containing hydrofluoric acid have the added disadvantage of being highly corrosive.

It is now been found by the practice of the present invention, that an aqueous fluoride-free formulation including phosphoric acid, a transition metal compound and a wetting agent effectively brightens and cleans aluminum surfaces by a method which includes the step of spraying or brushing the formulation while at a moderate temperature onto an aluminum containing surface. The formulation and method of the present invention overcome disadvantages inherent in previous attempts to clean and brighten aluminum surfaces. The present formulation may be effectively used in low concentrations at moderate temperatures whereas the present method is readily suited for treating large surfaces such as truck trailers and construction paneling without requiring size restrictive wash tanks.

Generally stated, the present invention provides a formulation which includes a transition metal compound, phosphoric acid, a wetting agent and water. In the method of the present invention, the formulation may be applied with or without dilution to an aluminum containing surface for a relatively short contact period after which the applied formulation is water rinsed from the surface. Aluminum or alloys thereof so treated may be found to be cleaned effectively and brightened both effectively and uniformly.

A transition metal compound such as nickel sulfate is found to be effective in the present formulation. Nickel sulfate'is believed to act as a catalyst in the present formulation and makes possible the use of low acid concentrations at moderate temperatures to effect the desirable cleaning and brightening. The present formulation desirably includes nickel sulfate in a concentration range from about 0.1 part by weight to about 5 parts by weight. Concentrations below this range are usually marginally effective whereas the increased benefits of nickel sulfate concentrations above 5 parts by weight are generally insufficient to justify the added cost thereof. The preferred nickel sulfate concentration is about 1 part by weight in the prepared formulation. Decreasing the concentration of the nickel sulfate is found to result in a sacrifice of brightening speed and uniformity.

The present formulation may be prepared using phosphoric acid in various concentrations, including, for example, 75 weight percent, 85 weight percent, and 105 weight percent. Phosphoric acid may be added in an amount from about parts by weight of 85 weight percent phosphoric acid to about 985 parts by weight of 85 weight percent phosphoric acid. More desirably the phosphoric acid concentration is in the range from about 66.5 parts by weight to about 98.5 parts by weight of 85 weight percent phosphoric acid. Decreasing the concentration of phosphoric acid may result in a sacrifice of brightening speed. For example, a formulation including about 30 parts by weight of 75 weight percent phosphoric acid may require an application temperature of about 180 F. to provide brightening comparable to that obtained at about 70 F. with a second formulation including similar parts of nickel sulfate, similar parts of a similar wetting agent, and about 98 parts by weight of weight percent phosphoric acid.

Brightening strength and speed comparable to that provided by a formulation including the preferred phosphoric acid content may be provided by a formulation having a substantially lower phosphoric acid content if a small amount of a strong mineral acid such as sulfuric acid, hydrochloric acid, nitric acid, or the like is included in the formulation. A comparably effective formulation may be prepared using from about 1 part by weight to about 10 parts by weight of a concentrated strong mineral acid to replace from about 5 parts by weight to about 30 parts by weight of 85 weight percent phosphoric acid.

Most any wetting agent which is stable in the presence of acids such as phosphoric, sulfuric, hydrochloric, nitric and the like is useful in the present formulation. Combinations of useful compatible wetting agents are also useful.

One class of useful wetting agents is manufactured by the Miranol Chemical Co. and is apparently represented by the following general formula:

where R 1 is the radical C H (a wetting agent identified by the trademark Miranol JS Conc.), where R is the radical C H (a wetting agent identified by either the trademark Miranol HS Conc. or Miranol CS Conc.), where R is the radical C H (identified by the trademark Miranol DS) or where R is the radical where R2 is the radical (identified by the trademark Miranol C2M Conc.),where R is the radical C H, (identified by the trademark Miranol J2M Conc.) or where R is the radical HH HH (identified by the trademark Miranol L2M SF).

Another class of Miranol Chemical Co. wetting agents useful in the present formulation may be represented by the following general formula:

where R is the radical C|1H23 (identified by either the trademark Miranol HM Conc. or Miranol CM Conc.) or R is the radical C|7H35 (identified by the trademark Miranol DM Various similar compounds manufactured by Miranol Chemical Co. are also useful in the present formulation.

Nonylphenoxypoly (ethyleneoxy) ethanol wetting agents are also useful in the present formulation. Numerous such wetting agents include a series of Igepal CO- trade marked products manufactured by GAF Corporation, for example, lgepal CO-710. Wetting agents selected from the straightchain-alkylphenoxypoly (ethyleneoxy) ethanol class are found to be particularly desirable in the present formulation. Examples of readily available wetting agents of this class include lgepal LO-630, Igepal LO-730 and lgepal LO-7 10, all of which are also trade marked products manufactured by GAF Corporation.

The wetting agent is desirably present in a range from about 0.1 part by weight to about 3 parts by weight. Preferably about 0.5 part by weight is included in the prepared formulation. Although concentrations below about 0.1 part by weight may be employed with some effectiveness, decreasing the concentration of the wetting agent is found to result in a decrease in the cleaning power of the formulation. Increases in cleaning power obtained with such wetting agents above about 3 parts by weight are generally overshadowed by the added cost thereof.

The formulation may be prepared by the addition of water, in excess of any water which may be in solution with the acid. Although most any concentration of water in the prepared formulation may be used, concentrations of added water in excess of about 67 parts by weight of the prepared formulation are found to be unnecessary. Although preferably no water is added in preparing the formulation, added water may be present in a concentration of up to about 30 parts by weight. The preferred formulation therefore is as follows:

The present formulation may be prepared by mixing the various ingredients in any sequence provided the well known precautions for mixing acids and water are followed.

The present method for brightening aluminum or its alloys with the formulation of the present invention may include a dilution step at the brightening site. Although dilution with more than 20 parts by weight of water per part of formulation may be useful in some instances, it is usually desirable to limit such dilution to a ratio of 20: 1. In using the preferred formulation, a dilution of 10 parts of water per part of formulation is preferred. A dilution of about 10:1 of water-to-formulation is found to produce an optimum brightening with a given amount of formulation. Dilution with only parts of water per part of formulation generally provides only a marginal increase in effectiveness, if any, over the :1 dilution and reduces the total surface which may be cleaned with a given amount of undiluted formulation. Use of the preferred formulation with no dilution may be found in some instances to provide less effective brightening than is possible with the dilution of 5: l of water-to-formulation.

The period of contact to be provided after application of the formulation will, of course, vary with the degree of contamination of the aluminum surface and with the degree of brightness desired. In many instances a period from about 5 minutes to about 10 minutes may be found to produce the desired cleaning and brightness. Application of the formulation may be effected by any suitable means such as spraying or brushing. Although the acid employed in the formulation is relatively weak and may, by dilution, be used in relatively low concentrations, rinsing is found desirable to eliminate any residual acid. The present fonnulation is safe and may provide clean, uniformly bright aluminum surfaces by application at ambient temperatures. Relatively large surfaces may be conveniently cleaned and brightened in place.

The formulation and method of the present invention will be further illustrated by the following examples. Practice of the present invention is demonstrated in connection with brightening sample panels having the following conventional U.S.A. nomenclature of the Aluminum Association for aluminum alloys:

2024, 5052, 2024 Alclad and 7075 Alclad. The samples are prepared by streaking the panels with a soiling agent formed of Bunker C fuel oil and a dispersion of carbon black in toluene.

EXAMPLE 1 A widely accepted active fluoride-containingphosphoric acid aluminum brightening product called Dyna Brite, manufactured by Du Bois Division of W. R. Grace & Co., Sharonville, Ohio is brushed onto samples of each of the four panels. Extreme care is taken to avoid personal contact with the formulation. After a work period of about 5 minutes the Dyna Brite is rinsed from the panels with tap water. Although the treated panels are found to be generally cleaned and brightened, dull streaks are apparent on the surface.

EXAMPLE 2 A formulation is prepared in the following weight proportions: 45.5 parts water, 515 parts 75 weight percent phosphoric acid, 1 part nickel sulfate, and 2 parts Igepal LO-7l0. Samples of each of the four panels are treated with this formulation at each of the following water dilutions:

l. undiluted,

2. in a 5: l weight ratio of water to formulation,

3. in a 10:1 weight ratio of water to formulation, and

4. a 20:] weight ratio of water to formulation. Treatment consists of applying this formulatiomin the various dilutions and at a moderate temperature, to each of the aforesaid panels;allowing a 5 minute work period; and subsequently rinsing each of the treated panels with tap water. At each of the four dilutions this formulation is found to generally provide effective brightening and removal of the Bunker C soil. Cleaning and brightening are found to increase with decreasing dilution. This formulation particularly at the 10:1 dilution of water-to-formulation, at the 5:1 dilution and at full concentration, is found to provide a more uniform brightening of the panel surfaces in comparison with the standard fluoride type brightener of Example 1.

EXAMPLE 3 A formulation is prepared in the following weight proportions: 30.5 parts water, 66.5 parts 75 weight percent phosphoric acid, 1.0 part nickel sulfate and 2.0 parts lgepal LO-7 10. Samples of each of the four panels are treated with this formulation according to the treatment used in Example 2 and at dilutions 1) through (4) set forth therein. This formulation is found to brighten faster than the formulation of Example 2. This concentrated formulation, diluted 5:1 and diluted 10:1 water-to-formulation is found equivalent to the standard fluoride product of Example 1 in the extent of brightening and superior in the uniformity of brightening.

EXAMPLE 4 A formulation is prepared in the following weight proportions: 1.5 parts water, 95.5 parts 75 weight percent phosphoric acid, 1.0 part nickel sulfate and 2.0 parts lgepal LO-7 10. Samples of each of the four panels are treated with this formulation according to the treatment used in Example 2 and at dilutions 1 through (4) set forth therein. This formulation, at the 10:1 dilution water-to-formulation and the 5:1 dilution is found to provide more efi'ective brightening than the standard fluoride product of Example 1 and in its undiluted form is found to provide equivalently effective brightening in comparison to the standard. At each of these three dilutions this formulation is found to be superior to the standard in uniformity of brightness attainable on each of the four types of alloy panels.

EXAMPLE 5 A formulation is prepared in the following weight proportions: 6.4 parts water, 91.5 parts 75 weight percent phosphoric acid, 01 part nickel sulfate and 2.0 parts lgepal LO-7 10. Samples of each of the four panels are treated with this formulation according to the treatment used in Example 2 and at dilutions (1) through (4) set forth therein. This formulation at each of the four dilutions is found to be a slightly less effective brightener and a less uniform brightener than the formulation in Example 4 at each of its respective concentrations. The difference is attributable to the lesser nickel sulfate concentration in this formulation.

EXAMPLE 6 A formulation is prepared in the following weight proportions: 1.5 parts water, 91.5 parts 75 weight percent phosphoric acid, 5.0 parts nickel sulfate, and 2.0 parts Igepal Lo-7l0. Samples of each of the four panels are treated with this formulation according to the treatment used in Example 2 and at dilutions 1) through (4) set forth therein. This formulation is found to be a more effective and more uniform brightener at each of the four dilutions in comparison to the respective dilutions of the formulation in Example 4. The difference is attributable to the greater nickel sulfate concentration in this formulation.

EXAMPLE 7 A formulation is prepared in the following weight proportions: 98.9 parts 85 weight percent phosphoric acid, 1.0 part nickel sulfate and 0.1 part Igepal LO-7l0. Samples of each of the four panels are treated with this fonnulation according to the treatment used in Example 2 at dilutions (1) through (4and at set forth therein. This formulation is found to be a marginally uniform brightener at each of its four dilutions. This is attributable to the low wetting agent concentration.

EXAMPLE 8 A formulation is prepared in the following weight proportions: 98.5 parts 85 weight percent phosphoric acid, 1.0 part nickel sulfate and 0.5 part lgepal LO -7l0. Samples of each of. the four panels are treated with this formulation according to the treatment used in Example 2 and at dilutions (1) through 4) set forth therein. At all four dilutions, this formulation is found to provide more effective cleaning and more uniform brightening than the standard brightener of Example 1. it is even found superior to the Example 4 formulation. The superiority over the Example 4 formulation is attributed to the greater amount of phosphoric acid. The increased brightening uniformity of this formulation in comparison with the Example 7 formulation is attributable to the greater lgepal LO-7l0 concentration.

EXAMPLE 9 A formulation is prepared in the following weight proportions: 68.5 parts water, 30.0 parts 75 weight percent phosphoric acid, 1.0 part nickel sulfate and 0.5 part Igepal LO-7 10. Samples of each of the four panels are treated with this formulation according to the treatment used in Example 2 and at dilutions 1) through (4) set forth therein. The aluminum alloy panels treated with this formulation are found to have a less bright appearance than is found using the Example 4 formulation, however, the brightening that does occur is relatively uniform. The difference in brightness is attributable to the much lower acid concentration in the Example 9 formulation.

EXAMPLE 10 Steam is mixed :1 with the formulation of Example 9 in a O steam gun and the mixture is applied to a 2024 aluminum alloy panel as a hot jet spray. Brightening is effective and rapid.

EXAMPLE 1 l A formulation is prepared in the following weight proportions: 44.0 parts water, 51.0 parts 75 weight percent phosphoric acid, 1.0 part nickel sulfate, 1.0 part Miranol J 2M Conc., 1.5 parts Miranol JS Conc. and 1.5 parts Miranol CS Conc. Samples of each of the four panels are treated with this formulation according to the treatment used in Example 2 and at dilutions 1) through 4) set forth therein. This formulation sufficiently wets the surface of the alloy panels and provides eflective cleaning thereof.

EXAMPLE 1 2 The formulation of Example 8, in each of the four therein stated dilutions, is applied at a moderate temperature to each of the four alloy panel samples. However, in this example application of the brightener is made by spraying. About 5 minutes after spraying the panels are rinsed with tap water. The spray application technique is found to produce both cleaning and brightening equivalent to the brush application technique of Example 8.

EXAMPLE 13 A formulation is prepared in the following weight proportions: 13.5 parts water, 80.0 parts 75 weight percent phosphoric acid, 5.0 parts concentrated sulfuric acid, 10 part nickel sulfate and 0.5 part Igepal CO-7l0. Samples of each of the four panels are treated with this formulation according to the treatment used in Example 2 and at dilutions (1) through (4) set forth therein. The aluminum alloy panels treated with this fonnulation are found to be cleaned and brightened with an effectiveness comparable to that which is observed for the Example 8 formulation.

It is to be understood that the foregoing description is given merely as an illustration of the present invention and that various modifications may be made therein without departing from the spirit thereof.

What is claimed is:

l. A method for cleaning and brightening an aluminum metal surface, said method consisting of:

A. applying to the aluminum metal surface a fluoride-free formulation with 10 parts water per part concentrate, said concentrate consisting essentially of 5 l .5 parts by weight taken as 75 percent phosphoric acid, 1 part by weight nickel sulfate, and 2 parts by weight nonylphenoxypoly( ethyleneoxy )ethanol surfactant;

B. permitting the applied formulation to remain in contact with said metal surface for a period of time sufficient to effect cleaning and brightening of the surface; and thereafter C. rinsing said formulation from said surface. 

